Sampling apparatus

ABSTRACT

An apparatus for use in and a method of sampling material on-line in a process system, comprising: a sample collector ( 1 ) including a wall member ( 8 ) of fixed position on which a sample of material is in use collected; a measuring device ( 3 ) for taking measurements from a collected sample; and sample displacing means for displacing the collected sample from the sample collector ( 1 ) so that the sample collector ( 1 ) can receive a new sample of material.

The present invention relates to an apparatus for and a method ofsampling material in a process system, in particular the on-linesampling of a flow of a liquid or powder.

Traditionally, a sample of material would have been removed duringprocessing from a process system and then analyzed. It will beappreciated that techniques requiring the removal of material from aprocess system for separate analysis are both labor-intensive and timeconsuming.

More recently, techniques have been developed which allow material to beanalyzed on-line. WO-A-96/12174 discloses an apparatus for the on-lineanalysis of material in a process system, specifically a reactionvessel. This apparatus comprises a probe, which is located in thereaction vessel and includes a chamber having openings through whichmaterial continuously passes, and optical measurement means foranalyzing the material passing through the chamber. WO-A-96/24835discloses an apparatus for the on-line analysis of material in a processsystem, specifically a tubular section. This apparatus comprises a tubehaving opposed transparent windows, a light source adjacent one windowand a photo-detector adjacent the other window, whereby the compositionof the material passing the windows is determined by the signalsgenerated by the photo-detector. Whilst these on-line techniques areless labor-intensive and allow for a more rapid analysis of material,such techniques still exhibit a number of problems. Notably, where aprobe is used to analyze a flow of material, it is often difficult tolocate the probe in a region of the material which flows continuouslyand steadily. In fact, it is commonly found that the probe will belocated in a region of the material which has a pulsed flow or is indeedstationary. It is also difficult to ensure that the probe iscontinuously surrounded by fresh material so that the on-goingmeasurement is truly representative of the entire bulk of material. Formany reasons, in these prior art techniques the same material can remainnext to the probe which leads to the analysis throughout the processcycle as characterizing the entire bulk of material as having the samecomposition when in fact the position could be quite different.

It is thus a general aim of the present invention to provide anapparatus for and a method of periodically sampling material on-linewhich is representative of the entire bulk of material from whichsamples are taken.

It is a particular aim of the present invention to provide a samplingapparatus which ensures a stable interface between the material to besampled and the measuring device. Where a flow of material is to besampled, it is desirable to present a stationary sample to the measuringdevice.

A further aim of the present invention is to provide a samplingapparatus which allows material to be sampled and replaced with newmaterial in a quick and efficient manner.

Accordingly, the present invention provides an apparatus for use insampling material on-line in a process system, comprising: a samplecollector including an upwardly-facing wall member of fixed position onwhich a sample of material is in use collected; a measuring device fortalking measurements from a collected sample; and sample displacingmeans for displacing the collected sample from the sample collector sothat the sample collector can receive a new sample of material. Inpreferred embodiments the process system is one of a process vessel or atubular section.

By virtue of the configuration of the sampling apparatus of the presentinvention, a relatively simple construction is provided which avoids theneed to remove material from the process system and allows for astationary sample to be presented to the measuring device. Theconstruction also allows for a collected sample from which measurementshave been taken to be replaced both simply and rapidly. In addition, theconfiguration of the sampling apparatus of the present invention is suchthat it is in effect self-cleaning, thereby minimizing the down-time ofthe process system from which material is being sampled. Moreover, thesampling apparatus of the present invention allows for the use of anykind of measuring device which utilizes electromagnetic radiation.

In one embodiment the sample displacing means comprises a pressurizedgas supply which in use is actuated to displace the collected sample.

As will be appreciated, this embodiment of the sampling apparatus of thepresent invention exhibits the particular advantage that sampling isachieved without requiring any moving parts or requiring the apparatusto introduce components into the material to be sampled which areelectrically operated, thereby minimizing the risk of an explosion.

Preferably, the measuring device is non-destructive or partiallydestructive.

In one embodiment the measuring device is a spectroscopic measuringdevice and can be a reflectance, transflectance or transmission device.Preferably, the spectroscopic measuring device is one of an emission,absorbtion or scattering device. In preferred embodiments thespectroscopic measuring device is an x-ray spectrophotometer, anultra-violet (UV) spectrophotometer, a visible (VIS) spectrophotometer,an infra-red (IR) spectrophotometer, a near infra-red (NIR)spectrophotometer, a raman spectrophotometer, a microwavespectrophotometer or a nuclear magnetic resonance (NMR)spectrophotometer.

In another embodiment the measuring device is a polarimeter.

In a preferred embodiment the measuring device includes a measurementprobe and the sample collector is attached to the distal end of themeasurement probe such as to be movable within the process system. Thisconfiguration is particularly useful when representative samples are notto be found adjacent the wall of a process system or if homogeneity isto be monitored at different locations within a process system.

In a preferred embodiment the sample collector is connected to aheating/cooling means so as to provide for temperature stabilization ofthe sample collector. Temperature stabilization can provide morereliable measurements where the measuring device is sensitive tovariations in temperature or where, for example, the material to besampled is a liquid which tends to boil, with the gas bubbles generatedadversely affecting the measurement

The present invention also provides a method of sampling materialon-line in a process system, comprising the steps of: collecting asample of material in a sample collector, the sample collector includingan upwardly-facing wall member of fixed position on which a sample ofmaterial is collected; taking measurements from the collected sample;and displacing the collected sample from the sample collector.

In a preferred embodiment the collected sample is displaced from thesample collector using a pressurized gas supply.

The present invention finds particular application in monitoring thecharacteristics, for example compositional changes, of pharmaceuticalcompositions typically in the form of powders, granules, pellets andtablets during preparation in fluidized beds. However, it will beappreciated that the present invention can equally be applied to otherprocesses within the pharmaceutical industry, and indeed innon-pharmaceutical processes. Other processes to which the presentinvention can be applied are typically blender systems, powder transportdevices, spray granulators, spray dryers and mixing/separation systems.

Preferred embodiments of the present invention will now be describedhereinbelow by way of example only with reference to the accompanyingdrawings, in which:

FIG. 1 schematically illustrates a sampling apparatus in accordance witha first embodiment of the present invention incorporated in a processvessel;

FIG. 2 illustrates a front view of the sampling apparatus of FIG. 1;

FIG. 3 illustrates a flow chart of a method of sampling material inaccordance with the present invention;

FIG. 4. schematically illustrates part of a sampling apparatus inaccordance with a second embodiment of the present invention at theperipheral wall of a process vessel;

FIG. 5 schematically illustrates part of a sampling apparatus inaccordance with a third embodiment of the present invention at theperipheral wall of a process vessel;

FIG. 6 schematically illustrates part of a sampling apparatus inaccordance with a fourth embodiment of the present invention at theperipheral wall of a process vessel, with the sample collector locatedin a first position adjacent the peripheral wall of the process vessel;

FIG. 7 schematically illustrates the part of the sampling apparatus ofFIG. 6, with the sample collector located in a second position distantfrom the peripheral wall of the process vessel; and

FIG. 8 illustrates a front view of the sampling apparatus of FIG. 6.

FIGS. 1 and 2 illustrate a sampling apparatus in accordance with a firstembodiment of the present invention.

The sampling apparatus comprises a sample collector 1 for collecting asample of material, a measuring device 3 for taking measurements from acollected sample, a sample displacement device 5 for displacing acollected sample from the sample collector 1 and a controller 6. Theoperation of each of the sample collector 1, the measuring device 3 andthe sample displacement device 5 is performed under the control of thecontroller 6, typically a computer or a programmable logic controller(PLC), as will be described in more detail hereinbelow.

The sample collector 1 is fixed to an inner surface of the peripheralwall 7′ of a process vessel 7. The sample collector 1, in thisembodiment an open-topped chamber, includes an arcuate wall member 8 onwhich powder is in use collected and a front wall member 9 which tapersupwardly and outwardly for assisting in guiding material thereinto.

The measuring device 3 includes a measurement probe 11, in thisembodiment a near infra-red reflectance probe, which extends through theperipheral wall 7′ of the process vessel 7 such that the distal end 13of the measurement probe 11, through which radiation is emitted andreceived, is directed into the sample collector 1. In this mannermeasurements can be taken from a sample of material collected in thesample collector 1.

The measuring device 3 further includes a radiation generating unit 15for generating electromagnetic radiation and a detector unit 17 fordetecting the radiation difffusely reflected by a collected sample.

In this embodiment the radiation generating unit 15 comprises in thefollowing order: a radiation source 19, preferably a broad spectrumvisible to infra-red source, such as a tungsten-halogen lamp, whichemits radiation in the near infra-red interval of from 400 to 2500 nm, afocusing lens 21, a filter arrangement 23 and at least one fiber cable25 for leading the focused and filtered radiation to distal end 13 ofthe measurement probe 11. In this embodiment the filter arrangement 23comprises a plurality of filters, each allowing the passage of radiationof a respective single frequency or frequency band. In other embodimentsa monochromator or a spectrometer of Fourier transform kind can be usedinstead of the filter arrangement 23.

In this embodiment the detector unit 17 comprises in the followingorder: an array of fiber cables 27, whose distal ends are arrangedaround the distal end of the at least one fiber cable 25 which suppliesradiation to a collected sample, and a detector 29 connected to thefiber cables 27. The detector 29 is preferably an array detector such asa CMOS chip, a CCD chip or a focal plane array. The distal ends of thefiber cables 27 are preferably spaced from the distal end of the atleast one fiber cable 25 in order to minimize the effect of specularreflection or stray energy reaching the fiber cables 27. In use, thedetector 29 will produce signals S depending upon the composition of thesampled material and the frequency of the supplied radiation. Thesesignals S are then amplified, filtered and digitized so as to beavailable for further processing. The processed signals can be used toperform real-time or subsequent analysis. Alternatively or additionally,the processed signals can be used for process control.

The sample displacement device 5 comprises a high-pressure gas source31, in this embodiment an air compressor, and a small bore tube 33 whichextends from the high-pressure gas source 31 through the peripheral wall7′ of the process vessel 7 to the sample collector 1. The distal end 35of the small bore tube 33 is directed downwardly into the samplecollector 1 such that, when pressurized gas is delivered therethrough,material resident in the sample collector 1 is displaced, that is, blownout, whereupon a new sample may be collected from which measurements canbe taken. By arranging the distal end 35 of the small bore tube 33 so asto be downwardly-directed the risk of material entering the small boretube 33 is minimized. In this embodiment the distal end 35 of the smallbore tube 33 is disposed adjacent the lowermost part of the uppersurface of the arcuate wall member 8 of the sample collector 1.Typically, the pressurized gas is at a pressure of the order of 1 barand is supplied for about 0.1 seconds. The pressure and the duration ofthe pressure pulse which has to be used will vary depending upon thematerial being sampled, but these parameters can be determined byroutine experimentation.

The sequence of operation of the sampling apparatus of FIGS. 1 and 2 isschematically illustrated in FIG. 3. In use, a sample is first collectedin the sample collector 1 (Step 1). The sampling apparatus is theninitiated to start measurement either automatically or by theintervention of an operator (Step 2). Under the control of thecontroller 6, measurements are then taken from the sample collected inthe sample collector 1 using the measuring device 3 to generate datacorresponding to the received radiation (Step 3). As the data isgenerated it is then either analyzed in real time or stored forsubsequent analysis (Step 4), with the resulting information optionallybeing used for process control. After all of the required measurementshave been taken from the sample, the controller 6 then actuates thesample displacement device 5 which in this embodiment actuates thehigh-pressure gas source 31, whereupon pressurized gas is deliveredthrough the small bore tube 33 into the sample collector 1 and thesample resident in the sample collector 1 is displaced such that a newsample can be collected (Step 5). The sampling method can then berepeated to take measurements from another sample of material.

FIGS. 4 to 8 respectively illustrate sampling apparatuses or partsthereof in accordance with second to fourth embodiments of the presentinvention. These sampling apparatuses are quite similar structurally andoperate in the same manner as the sampling apparatus in accordance withthe first embodiment of the present invention as described hereinabovein relation to FIGS. 1 to 3. Hence, in order not to duplicatedescription unnecessarily, only the structural differences of thesampling apparatuses of these further embodiments will be described. Itwill of course be appreciated that features of the sampling apparatusesof these further embodiments and the sampling apparatus of theembodiment of FIGS. 1 and 2 can be used in conjunction with one another.

FIG. 4 illustrates part of a sampling apparatus in accordance with asecond embodiment of the present invention and incorporates atransflective measuring device. This sampling apparatus differs fromthat of the first embodiment of the present invention in that themeasurement probe 11 does not extend into the sample collector 1 and inthat a reflective surface 37, typically a mirrored surface, is providedon the inner side of the sample collector 1 opposed to the path of theradiation supplied by the at least one fiber cable 25. In order to allowtransmission of radiation from the measurement probe 11 into the samplecollector 1, the peripheral wall 7′ of the process vessel 7 is providedwith a window 39 which is transparent or at least translucent to theradiation employed by the measuring device 3. In use, radiation providedby the at least one fiber cable 25 passes through a sample of materialcollected in the sample collector 1 and is reflected back to the fibercables 27 by the reflective surface 37.

FIG. 5 illustrates part of a sampling apparatus in accordance with athird embodiment of the present invention and incorporates atransmissive measuring device. This sampling apparatus differs from thatof the first embodiment of the present invention in that the measurementprobe 11 does not extend into the sample collector 1 and in that thedistal ends of the fiber cables 27 are located at the inner side of thesample collector 1 opposed to the path of the radiation supplied by theat least one fiber cable 25. Similarly to the embodiment of FIG. 4, inorder to allow transmission of radiation from the measurement probe 11into the sample collector 1, the peripheral wall 7′ of the processvessel 7 is provided with a window 39 which is transparent or at leasttranslucent to the radiation employed by the measuring device 3. In use,radiation provided by the at least one fiber cable 25 passes through asample of material collected in the sample collector 1 and is detectedby the fiber cables 27.

FIGS. 6 to 8 illustrate part of a sampling apparatus in accordance witha fourth embodiment of the present invention. This sampling apparatusdiffers from that of the first embodiment of the present invention inthat the sample collector 1 is mounted to the distal end 13 of themeasurement probe 11 and in that the measurement probe 11 and the smallbore tube 33 of the sample displacement device 5 are provided in a slidebody 40 which is slideably mounted in the wall 7′ of the process vessel7. In this way, the sample collector 1 can be located at a range ofpositions relative to the wall 7′ of the process vessel 7 so as to allowmeasurements to be taken from samples at those positions. The samplingapparatus further differs from that of the first embodiment of thepresent invention in that the distal end 13 of the measurement probe 11includes an element 41 which is transparent or at least translucent tothe radiation employed by the measuring device 3 and acts as a means ofprotection for the fiber cables 25, 27. This sampling apparatus yetfurther differs from that of the first embodiment of the presentinvention in that a block of material 47 of known characteristic, suchas polystyrene, is provided on the inner side of the sample collector 1opposed to the path of the radiation supplied by the at least one fibercable 25. The block 47 serves as a standard which enables the samplingapparatus to be calibrated when the sample collector 1 is empty. In thisway, the measurement probe 11 can be calibrated in situ.

Finally, it will be understood by a person skilled in the art that thepresent invention is not limited to the described embodiments but can bemodified in many different ways without departing from the scope of theinvention as defined in the appended claims.

What is claimed is:
 1. An apparatus for use in sampling material on-linein a process system, comprising: a sample collector comprising anopen-topped chamber having an arcuate wall member for receiving a sampleof material, and a front wall member which is flared upwardly andoutwardly; a measuring device comprising a measurement probe for takingmeasurements from a collected sample; and sample displacing means fordisplacing the collected sample from the sample collector so that thesample collector can receive a new sample of material.
 2. The apparatusaccording to claim 1 incorporated in a process system, wherein thesample collector is located within the process system.
 3. The apparatusaccording to claim 2, wherein the sample collector is movable relativeto an inner surface of the process vessel.
 4. The apparatus according toclaim 2, wherein the sample collector is located adjacent an innersurface of the process vessel.
 5. The apparatus according to claim 2,wherein the sample collector is fixed to an inner surface of the processvessel.
 6. The apparatus according to claim 2, wherein the processsystem comprises a process vessel.
 7. The apparatus according to claim2, wherein the process system comprises a tubular section.
 8. A methodof sampling material on-line in a process system, comprising the stepsof: collecting a sample of material in a sample collector, the samplecollector comprising an open-topped chamber having an arcuate wallmember on which a sample is collected and a front wall member which isflared upwardly and outwardly for receiving a sample in a process vesselof the process system; taking measurements from the collected samplewith a measuring device comprising a measurement probe which extendsinto the process vessel; and displacing the collected sample from thesample collector.
 9. The method according to claim 8, wherein theprocess system comprises a process vessel.
 10. The apparatus accordingto claim 1, wherein the sample displacing means comprises a pressurizedgas supply which is actuated to displace the collected sample when theapparatus is in use.
 11. The apparatus according to claim 10, whereinthe pressurized gas supply comprises a tube whose distal end is directedat the sample collector.
 12. The apparatus according to claim 11,wherein the distal end of the pressurized gas supply tube is locatedadjacent an upper surface of the sample collector.
 13. The apparatusaccording to claim 12, wherein the distal end of the pressurized gassupply tube is located adjacent a lowermost part of the upper surface ofthe sample collector.
 14. The apparatus according to any one of claims1, 10, 11, 12, or 13, wherein the measuring device is a polarimeter. 15.The apparatus according to any one of claims 1, 10, 11, 12 or 13,wherein the measuring device is a spectroscopic measuring device. 16.The apparatus according to claim 15, wherein the spectroscopic measuringdevice is one of a reflectance, transflectance or transmission device.17. The apparatus according to claim 16, wherein the spectroscopicmeasuring device comprises an infra-red spectrophotometer.
 18. Theapparatus according to claim 16, wherein the spectroscopic measuringdevice comprises a near infra-red spectrophotometer.
 19. The apparatusaccording to claim 16, wherein the spectroscopic measuring devicecomprises an x-ray spectrophotometer.
 20. The apparatus according toclaim 16, wherein the spectroscopic measuring device comprises avisible-wavelength spectrophotometer.
 21. The apparatus according toclaim 16, wherein the spectroscopic measuring device comprises a ramanspectrophotometer.
 22. The apparatus according to claim 16, wherein thespectroscopic measuring device comprises a microwave spectrophotometer.23. The apparatus according to claim 16, wherein the spectroscopicmeasuring device comprises a nuclear magnetic resonancespectrophotometer.
 24. The apparatus according to claim 15, wherein thespectroscopic measuring device comprises an infra-red spectrophotometer.25. The apparatus according to claim 15, wherein the spectroscopicmeasuring device comprises a near infra-red spectrophotometer.
 26. Theapparatus according to claim 15, wherein the spectroscopic measuringdevice comprises an x-ray spectrophotometer.
 27. The apparatus accordingto claim 15, wherein the spectroscopic measuring device comprises avisible-wavelength spectrophotometer.
 28. The apparatus according toclaim 15, wherein the spectroscopic measuring device comprises a ramanspectrophotometer.
 29. The apparatus according to claim 15, wherein thespectroscopic measuring device comprises a microwave spectrophotometer.30. The apparatus according to claim 15, wherein the spectroscopicmeasuring device comprises a nuclear magnetic resonancespectrophotometer.
 31. The apparatus according to any one of claims 2,6, 7, 3, 4 or 5, wherein the measurement probe extends into the processsystem and the sample collector is fixed to the distal end of themeasurement probe.
 32. The apparatus according to any one of claims 2,6, 7, 3, 4 or 5, wherein the measuring device is located outside theprocess system and the process system includes at least one windowtransparent or at least translucent to the radiation used by themeasuring device through which measurements of a collected sample aretaken.
 33. The method according to claim 8, wherein the process systemcomprises a tubular section.
 34. The method according to claim 8,wherein the collected sample is displaced from the sample collectorusing a pressurized gas.
 35. The method according to claim 33 or 34,wherein material is sampled from a flow of material.